EHX has been around a long time. They are quality, vintage style and new effects. I think they are really meant more for gigging musicians, rather than studio work.
The units are durable and sound great, but can be noisy in the signal chain. That's why I say they might be more for gigging musicians. You wouldn't want to record the noise from your sound for posterity, unless that was your intent. If so, then go for it!
If a Big Muff has the sound you need, Live or Studio, then that's it. Job Done.